Comparison of three Mexican aluminosilicates for the sorption of cadmium

Summary The sorption of cadmium from aqueous solutions was evaluated in three Mexican aluminosilicates (two zeolites and one clay). The effects of pH and contact time on the sorption process were examined. Cadmium was analyzed by neutron activation analysis in the exchanged aluminosilicates. The sorption of cadmium by aluminosilicates was the same in the pH range from 4 to 8, considering the standard deviation. Kinetic studies were carried out and showed a rapid sorption of cadmium in the first 5 hours but the equilibrium was reached in about 20 hours. The sorption kinetics of cadmium ions was best described by the second-order Ritchie modified model. The experimental results obtained in different concentrations and at room temperature for both zeolites were fitted with classical isotherms of Freundlich, Langmuir and Freundlich-Langmuir models. The sorption pattern followed the Langmuir-Freundlich model.